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A colloidal crystal is an ordered array of colloidal particles and fine grained materials analogous to a standard crystal whose repeating subunits are atoms or molecules. [1] A natural example of this phenomenon can be found in the gem opal, where spheres of silica assume a close-packed locally periodic structure under moderate compression.
Quantum dots have been gaining interest from the scientific community because of their interesting optical properties, the main being band gap tunability. When an electron is excited to the conduction band, it leaves behind a vacancy in the valence band called hole. These two opposite charges are bound by Coulombic interactions in what is ...
The optical properties of a material define how it interacts with light. The optical properties of matter are studied in optical physics (a subfield of optics) and applied in materials science. The optical properties of matter include: Refractive index; Dispersion; Transmittance and Transmission coefficient; Absorption; Scattering; Turbidity
The approximation holds for particles of arbitrary shape that are relatively small but can be larger than Rayleigh scattering limits. [1] The theory was derived by Lord Rayleigh in 1881 and was applied to homogeneous spheres, spherical shells, radially inhomogeneous spheres and infinite cylinders. Peter Debye has contributed to the theory in 1881.
The Tyndall effect is light scattering by particles in a colloid such as a very fine suspension (a sol). Also known as Tyndall scattering , it is similar to Rayleigh scattering , in that the intensity of the scattered light is inversely proportional to the fourth power of the wavelength , so blue light is scattered much more strongly than red ...
Platinum NPs exhibit fascinating optical properties. Being a free electron metal NP like silver and gold, its linear optical response is mainly controlled by the surface plasmon resonance (SPR). Surface plasmon resonance occurs when the electrons in the metal surface are subject to an electromagnetic field that exerts a force on the electrons ...
A colloid is stable if the interaction energy due to attractive forces between the colloidal particles is less than kT, where k is the Boltzmann constant and T is the absolute temperature. If this is the case, then the colloidal particles will repel or only weakly attract each other, and the substance will remain a suspension.
As many properties of colloidal suspensions depend on the state of aggregation of the suspended particles, various indirect techniques have been used to monitor particle aggregation too. While it can be difficult to obtain quantitative information on aggregation rates or cluster properties from such experiments, they can be most valuable for ...